Gene therapy for hemophilia: new success

Hemophilia, a genetic disorder, has seen considerable advances in treatment over the past 50 years. A recently published article reports very encouraging results in hemophilia B following treatment with gene therapy.

Hemophilia, a 𝐠𝐞𝐧𝐞𝐭𝐢𝐜 𝐛𝐥𝐞𝐞𝐝𝐢𝐧𝐠 𝐝𝐢𝐬𝐨𝐫𝐝𝐞𝐫 with X-linked recessive inheritance, is caused by a 𝐝𝐞𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐲 𝐢𝐧 𝐚 𝐜𝐥𝐨𝐭𝐭𝐢𝐧𝐠 𝐟𝐚𝐜𝐭𝐨𝐫: factor VIII for hemophilia A and factor IX for hemophilia B. Hemophilia A affects 1 in 5,000 boys, while hemophilia B, a rarer form, affects 1 in 30,000 male births. The severity of hemophilia is 𝐩𝐫𝐨𝐩𝐨𝐫𝐭𝐢𝐨𝐧𝐚𝐥 𝐭𝐨 𝐭𝐡𝐞 𝐟𝐚𝐜𝐭𝐨𝐫 𝐈𝐗 𝐨𝐫 𝐕𝐈𝐈𝐈 𝐝𝐞𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐲. Women can also be affected, but as hemophilia is very often mild, it can therefore go unnoticed for a long time.

Gene therapy for the treatment of hemophilia aims to 𝐬𝐲𝐧𝐭𝐡𝐞𝐬𝐢𝐳𝐞 𝐭𝐡𝐞 𝐝𝐞𝐟𝐢𝐜𝐢𝐞𝐧𝐭 𝐟𝐚𝐜𝐭𝐨𝐫 in the liver to compensate for the deficiency. A recent study published in the 𝑁𝑒𝑤 𝐸𝑛𝑔𝑙𝑎𝑛𝑑 𝐽𝑜𝑢𝑟𝑛𝑎𝑙 𝑜𝑓 𝑀𝑒𝑑𝑖𝑐𝑖𝑛𝑒 reported the results of a 𝟏𝟑-𝐲𝐞𝐚𝐫 𝐟𝐨𝐥𝐥𝐨𝐰-𝐮𝐩 of patients with hemophilia B who had received an injection of an adenovirus enabling the synthesis of factor IX. The results are clear: 13 years after a single administration of the adenovirus, 𝐬𝐮𝐬𝐭𝐚𝐢𝐧𝐞𝐝 𝐞𝐱𝐩𝐫𝐞𝐬𝐬𝐢𝐨𝐧 𝐨𝐟 𝐟𝐚𝐜𝐭𝐨𝐫 𝐈𝐗 𝐚𝐧𝐝 𝐬𝐮𝐬𝐭𝐚𝐢𝐧𝐞𝐝 𝐜𝐥𝐢𝐧𝐢𝐜𝐚𝐥 𝐛𝐞𝐧𝐞𝐟𝐢𝐭 were observed, with no long-term adverse effects.

These results represent 𝐫𝐞𝐚𝐥 𝐡𝐨𝐩𝐞 for patients with severe hemophilia B. However, this treatment is also the 𝐦𝐨𝐬𝐭 𝐞𝐱𝐩𝐞𝐧𝐬𝐢𝐯𝐞 on the market today, costing around €3 million.